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Voice over Internet Protocol (VoIP) is an emerging technology with the potential to assist the United States Marine Corps in solving communication challenges stemming from modern operational concepts. This thesis conducts a review of VoIP standards and develops an H.323-based testbed for the study of tactical wireless VoIP performance. Methods of collecting and presenting voice quality parameters in packet-based networks are explored. Incorporation of an Adtech SX/14 Data Channel Simulator provides user control of a SONET-simulated wireless channel. Experiments quantify the effect of channel injected error rate on received voice traffic. Plots are generated to illustrate the relationship between channel error rate, packet loss, and the listening quality mean opinion score. Experimental results are extended by incorporating E-model delay considerations. Commercial voice recognition software is successfully used to measure the impact of the channel on speech intelligibility. The experiments and analysis conducted provide a cost effective approach to non-intrusive, objective voice quality assessment. |
